Semiconductor processing requires close temperature control for high temperature processes. High temperatures are used in various steps in semiconductor manufacturing including Rapid Thermal Processing, epilayer growth, structure processing, and bum-in, among others. Poor temperature control could lead to off-spec layer thickness, diffuse doping, and structural flaws, among others. In general, poor temperature control may lead to low yield.
However, typical measuring techniques are invasive, slow, and difficult to interpret. Thermocouples do not respond fast enough to be used in rapid thermal processing. Further, they must be located in the chamber and on the wafer.
Optical pyrometers are based on the thermal radiation of the wafer. The thermal radiation is strongly affected by the emissivity of the wafer. The emissivity of the wafer is a function of film depositions, backside roughness, doping levels, and temperature, among others. The pyrometers may also be affected by heat lamp radiation.
In addition, other acoustic techniques require contact with the wafer and must be located in the chamber. They are invasive and require contact.
As such, these techniques are not suitable for use in process control. The slow testing time may not provide enough information for process control applications. Further, a lack of automation in the analyzing the results limits applicability to process control. In addition, contact with the part may not be suitable, preventing the technique from use in the process.
As such, many typical NDE techniques suffer from deficiencies in speed and automation. Many other problems and disadvantages of the prior art will become apparent to one skilled in the art after comparing such prior art with the present invention as described herein.